JPS6229858B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron gun for a cathode ray tube. Generally, an electron gun is used in a cathode ray tube, and the main parts of a conventional electron gun built into, for example, a monochrome television picture tube are constructed as shown in FIG. That is, the directly heated cathode 1, the first grid electrode 2, the second to
Fourth grid electrodes (not shown) are sequentially arranged coaxially at predetermined intervals and fixed to an insulating support rod (not shown). In this case, the directly heated cathode 1 includes an insulating substrate 4 made of ceramics having grooves 3 for preventing leakage caused by vapor deposition of an electron-emitting substance, a pair of filament support rods 5 implanted opposite to the insulating substrate 4, and It consists of a filament 6 stretched over a filament support rod 5, a base metal plate 7 provided on the filament 6, and an electron emitting material 8 coated on the base metal plate 7. Such a directly heated cathode 1 is disposed within a first grid electrode 2 having a closed cylindrical shape,
It is maintained at a predetermined distance from the first grid electrode 2 by a spacer 9 made of metal, and is supported and fixed by a retainer 10. Note that 11 in the figure is an electron beam passage hole. Next, the manufacturing method (assembly method) of the above conventional electron gun
The main process order is explained below. A pair of filament support rods 5 is fixed to the insulating substrate 4 by glass attachment. An electron emitting substance 8 is applied to the surface of a base metal plate 7 fixed to a filament 6. The process filament 6 is stretched on the process filament support rod 5. A spacer 9 is placed inside the first grid electrode 2. The cathode 1, that is, the insulating substrate 4 that has undergone the process is placed inside the first grid electrode 2 that has undergone the process. The retainer 10 is placed in the first grid electrode 2 after the process, in contact with the insulating substrate 4, and is fixed to the first grid electrode. By the way, in the conventional electron gun having the above structure, the electron emitting material 8 is evaporated and deposited on the insulating substrate 4 during operation. As a result, leakage occurs along the path of filament support rod 5 - vapor deposition surface of insulating substrate 4 - spacer 9 - first grid electrode 2. Therefore,
In order to prevent this leakage, the grooves 3 are bored in the insulating substrate 4 as described above. This is undesirable because it tends to cause deformation after firing, resulting in poor dimensional tolerances.
Furthermore, manufacturing an electron gun requires many man-hours and is complicated. An object of the present invention is to provide an electron gun for a cathode ray tube that eliminates the above-mentioned conventional drawbacks. Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. In order to improve the above-mentioned conventional drawbacks, the electron gun of the present invention improves the shape of the spacer,
It is integrated with a directly heated cathode, and only the vicinity of the directly heated cathode will be illustrated and explained. That is, the directly heated cathode in the electron gun of the present invention is constructed as shown in FIG. 2, and FIGS. 3 and 4 are exploded views. First, the insulating substrate 12 is made of ceramics, and as shown in FIG. 3, it is a plate of a predetermined thickness and has notches 12a and 12b at both ends approximately at the center.
is formed, and a notch 12c is also formed at one end. A pair of filament supports 13 and 14 are implanted through the insulating substrate 12 so as to face each other at a predetermined distance. A filament 15 is stretched between the filament supports 13 and 14. In this case, one end of the filament 15 is fixed to the rod-shaped filament support 13, and the other end is provided with a notch 1.
It is fixed to the cylindrical filament support 14 via a spring 16 located at 2c, and the vicinity of this other end is in contact with the tip of a movable adjustment rod 17 located within the filament support 14. Further, a base metal plate 18 is fixed to the filament 15 approximately at the center, and an electron emitting material 19 is coated on the base metal plate 18. Further, a spacer 20 , which is a feature of the present invention, is integrally fixed to the insulating substrate 12. The purpose of this spacer 20 is to maintain a predetermined distance between the electron emitting material 19 of the cathode and the first grid electrode 2 (see FIG. 1), and to prevent the electron emitting material 19 from being deposited on the insulating substrate 12. , is constructed as shown in FIG. That is, the spacer body 21 is formed of a plate and has a size large enough to cover at least a region where the electron emitting material 19 is deposited on the insulating substrate 12. A plurality of, for example, four, first grid electrode contact portions 22 are integrally provided on one surface of the spacer body 21, and a plurality of insulating substrate contact portions 23 are provided on the other surface. In this case, in this embodiment, both ends of the spacer body 21 are connected to the insulating substrate 12.
First, the insulating substrate contact portion 23 is formed by extending and bending the insulating substrate contact portion 23 integrally in the opposite direction, and this insulating substrate contact portion 23 is then extended in the opposite direction and bent inward, and this bent portion is used as the first grid electrode contact portion 22. There is. Therefore, when the spacer 20 is fixed to the insulating substrate 12, the spacer main body 21 is lifted from the surface of the insulating substrate 12. Moreover, it is preferable that the insulating substrate contact portion 23 be located at a certain distance from the filament supports 13 and 14. Further, the spacer main body 21 has mounting portions 24 formed by extending and bending the vicinity of the center of both ends toward the insulating substrate contact portion 23 . These two mounting portions 24 are fitted into notches 12a and 12b bored at the substantially central end of the insulating substrate 12, and
By bending the spacer 2 to the back side of the spacer 2 ,
0 is integrally fixed to the insulating substrate 12. still,
Since the components other than the directly heated cathode are the same as those of the prior art, their explanation will be omitted. Next, the main steps of the manufacturing method (assembling method) of an electron gun equipped with a directly heated cathode as described above will be explained as follows. A pair of filament supports 1 on an insulating substrate 12
3 and 14 are fixed with glass. The spacer 20 is attached to the insulating substrate 12 in the process. Base metal plate 1 fixed to filament 15
An electron emitting material 19 is applied to the surface of 8. The filament 15 of the process is stretched on the filament supports 13 and 14. The position of the electron emitting material 19 is adjusted by the adjusting movable rod 17 of the filament support 14. The cathode insulating substrate 12 after the process is placed inside the first grid electrode. Note that the above steps may be reversed. The electron gun assembly of the present invention is constructed as described above and shown in the drawings, and a spacer 20 having a spacer body 21 that covers at least a large part of the vapor deposition region of the electron emitting material 19 on the insulating substrate 12 is used as a directly heated cathode. Since it is integrated into one, electron emitting material 1
Even if 9 evaporates, the amount of evaporation on the insulating substrate 12 is very small. That is, the spacer 20 is located between the pair of filament supports 13 and 14 and has a substantially U-shape so as to surround the bottom and both sides of the filament 15, and has a part of the bottom that abuts the surface of the insulating substrate 12. The spacer is formed with bent insulating substrate contact portions 23 and 26 that lift the spacer from the insulating substrate as a lever, and is fixed to the insulating substrate by a mounting portion 24 that is integrally formed with the spacer and extends downward. The ends of both side walls are bent to form the first
A first grid electrode contact portion 22 that contacts the grid electrode is formed. Therefore, the spacer has the function of shielding the evaporated material from adhering to the substrate surface and maintaining the distance between the grid electrode and the base metal plate. Therefore, the leakage between the cathode and the first grid electrode 2, which has conventionally been observed, is eliminated, and as a result, there is no need to drill a groove in the insulating substrate 12 to prevent leakage. Therefore, manufacturing of the insulating substrate 12 has become extremely easy. The insulating substrate 12 can be made into a flat shape, preventing bending during firing of ceramics and improving quality. Furthermore, according to the present invention, the retainer 10 used conventionally is not necessarily required. Further, the electron gun of the present invention is assembled by the process described above, and as is clear from the comparison with the conventional process, the process is significantly shortened and a significant cost reduction can be achieved. Incidentally, FIG. 5 shows a modification of the present invention, and FIG. 6 only shows the spacer 25. In this modification, step portions are formed in each of the mounting portions 24 of the spacer 25, and these step portions serve as insulating substrate contact portions 26, and the spacer body 21 is lifted above the insulating substrate 12 by the insulating substrate contact portions 26.
Of course, it goes without saying that the same effects as in the above embodiment can be obtained in this modification as well. Furthermore, in the above embodiments and modified examples, the mounting portion 24 was integrated with the spacer body 21, but the mounting portion 2
4 may be omitted, a separate mounting band may be prepared, and the spacer may be mounted to the insulating substrate 12 using this mounting band. Moreover, the directly heated cathode in the electron gun of this invention is
It can also be applied to a three-electron gun for color television picture tubes. As explained above, according to the present invention, it is possible to provide an electron gun for a cathode ray tube with great practical value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a conventional electron gun, FIG. 2 is a perspective view showing the main parts (near the directly heated cathode) of an electron gun according to an embodiment of the present invention, and FIGS. Figure 4 is an exploded perspective view of Figure 2 showing each part;
FIG. 5 is a perspective view showing a modification of the invention, and FIG. 6 is an exploded perspective view of FIG. 5 showing only the parts (spacer). 12... Insulating substrate, 13, 14... Filament support, 15... Filament, 16... Spring, 17... Adjustable movable rod, 18... Base metal plate, 19... Electron emitting material, 20 ... Spacer ,
21... Spacer main body, 22... First grid electrode contact portion, 23... Insulating substrate contact portion.

Claims (1)

[Scope of Claims] 1. An insulating substrate disposed within the first grid electrode, a pair of filament supports that are implanted through the insulating substrate at a predetermined distance, and a pair of filament supports that are stretched across the filament supports. a base metal plate fixed approximately at the center of the filament and coated with an electron-emitting substance; and a base metal plate interposed between opposing surfaces of the first grid electrode and the insulating substrate, the first grid electrode and the base metal plate being interposed between opposing surfaces of the first grid electrode and the insulating substrate. a spacer for maintaining a gap between the plates; the spacer includes a plate-shaped spacer body located between the filament and the insulating substrate and between the pair of filament supports; and a part of the spacer body. a plurality of insulating substrate contact portions that come into contact with the insulating substrate surface and lift the spacer body from the insulating substrate; and a plurality of insulating substrate contact portions that are integrally bent and extended from both ends of the spacer body in a direction opposite to the insulating substrate. and the first one, the end of which is further bent.
An electron gun for a cathode ray tube, comprising: a grid electrode contact portion; and a mounting portion provided on the spacer body and fixed to the insulating substrate.